Firch Engineering and Consulting Limited

28/11/2025

Part 4 : Dear Young Civil Engineer

In part 3 I discussed some important aspect of field work that are mostly neglected by young engineers. This part 4 is a continuation of those neglected aspects.

The time it took the heavy duty machines (eg excavator, pay loader, backhoe, etc) to work on site is vital in planning daily work on site. It's important too in preparing work schedule. Hence on site take note of what each machine can do or deliver per hour. Plot the graph of work done against time. This is why you are taught statistics (mean, standard deviation, variance,etc) in school. The graph will show you the peak periods and the lowest period.

Also note the time it took your workers (especially skilled labour) to deliver and quantity delivered. Plot the graph and note the lowest and the peak periods.

Question : You are given 3km of drain to construct, how long will it take to complete the project?

Assumptions :

excavator can do 100m a day.
Mobile mixer (5cum) 200 bags a day mix ratio : 1:2:4
one carpenter can do 15m a day and
one iron bender 10m a day

Machine and Labour on site
one excavator
one mobile mixer
8 carpenters
8 iron benders

All materials were delivered on time.

20/11/2025

Part 3 : Dear Young Civil Engineer

Supervising the various work activities on site is good. Checking for alignment of columns, bricks, drainages, etc are important. Making sure that the right mix ratios are used both in concrete and in mortar cannot be overemphasized.

However there are other details you should pay attention to that most times you may neglect. That is the aspect that will help you in both budgeting and forecasting in a project.

The trucks that deliver sand and granite to the site, check the waybill to know the tonnage. Also use your measuring tape to get the volume of the trucks. These will help you to calculate (both in cubic meter an in tons) the number of trucks needed for the project.

Start to measure the are sizes of materials like bricks, woods, boards, rebars, props, roof covers, tiles,etc. This is another tip that will help to prepare your take-off sheet. For instance : if you are asked the number of boards needed for the top slab of a culvert of 2.0m x 8m. (size of board 1.2 x 2.4m).

Solution
Area of top slab = 2*8 = 16sqm
Area of one board = 1.2*2.4 = 2.88sqm

The no of boards needed : 16/2.88 = 5.56 boards. Say 6 boards.

In Part 4... I will discuss those details that will help you in forcasting.

18/11/2025

The First 4 Semester Physics and the Young Civil Engineer.

My dear young civil engineer, every course you did in school prepares you for the field practice and the office practice. The elementary physics and the advanced physics you did in school are also inclusive.

The specific weight of various materials you studied are paramount to the loading of any structural elements in civil engineering. Most loading comes in kilonewton, kilonewton per meter and kilonewton per square meter. You multiply the specific weight of load by height or thickness to convert to kilonewton per square(mostly slab uniformly distributed load). Solving for Kilonewton per meter, multiply by area ( mostly beam uniformly distributed load) . To convert to kilonewton multiply the specific weight of the load by the volume of the load (mostly column load).

Also all those formulas associated with the wind are essentially in the design of high rise buildings. Shear force and Bending moments are first introduced in physics.

Theories you learnt in school mould you better as a civil engineer than the field experience.

Theory 60% Practical 40%

17/11/2025

Dear Young Civil Engineer (Part 2)

The mathematics courses you studied in your first four semesters is vital to preparing the Bill of Quantity or Bill of Engineering Measurements and Evaluation. The quantities in the bill are in length, area, volume,etc. This is where mensuration comes in.

All those find x and y have a lot to do with extracting the quantities of materials from the drawing. For instance, what's the number of blocks required to cover a room with total perimeter 15m and height 3m.
Let the number of blocks be x.
Total area of the room walls = 15 * 3 = 45sqm
Area of(face of a block in Nigeria) a block = 0.101sqm (0.225 * 0.45)
Now solving for x :
1 block = 0.101sqm
x blocks = 45sqm
Therefore x = 45 * 1 /0.101 = 445.545, say 450
Hence 450 blocks is required.

Remember how to solve your ratios? Don't forget it. 10 biscuits were shared to Ben, Judith and Frank in the ratio of 1:2:4. Find the number of biscuits each of them gets. This is similar to extracting the quantities of cement, sand and granite in a mixture of 1:2:4 concrete (with density 2,400kg/cum)
cum : cubic meter.

The theories you were thought in school will mould you more as a civil engineer than the site experience.

Theory 60% Practical 40%

13/11/2025

Dear Young Civil Engineer

Do not joke with the theories you learnt in school. Infact continue to read your notes and text books. The practical knowledge is important but the theory is more important than the practical to you as an engineer. Solving structural analysis that you will use to plot bending moment and shear force diagrams is paramount to building and highway structures. Mastering mass haul diagrams in road designs is vital too.

Softwares are good. However if you do not know your theory (or manual design) well, the software may lead you into an uneconomical design or under-design. Knowing your theory will help you to know the codes used by the software (in case if it's not applicable to your country) .

I will advice 60% theory and 40% practical to an aspiring civil engineer

13/09/2025

27/08/2025

𝐔𝐧𝐝𝐞𝐫𝐬𝐭𝐚𝐧𝐝𝐢𝐧𝐠 𝐂𝐞𝐦𝐞𝐧𝐭 𝐠𝐫𝐚𝐝𝐞𝐬!

🌹A lot of people are still confuse which one to go for between Dangote, BUA, Lafarge, Ashaka, UniCem, supaset etc. as “types of cement.” That is wrong.
These are only companies producing cement.

🌹What matters for your building is the cement grade, the strength of the cement, usually written as 32.5, 42.5, or 52.5 on the bag.

📍Grade 22.5👇
Rarely used in Nigeria. Mainly for very light works like plastering small structures.

📍Grade 32.5👇
Suitable for plastering, tiling, flooring, and non-structural works. Not recommended for beams, slabs, or load-bearing columns.

📍Grade 42.5👇
The most commonly used in Nigeria. Suitable for block molding, beams, slabs, columns, foundations, normal residential houses, schools, and small commercial buildings.

📍Grade 52.5👇
High strength cement. Used for bridges, high-rise buildings, dams, industrial structures, and projects requiring very high load capacity.

Important note: Always read the cement bag. Don’t just say “Give me Dangote or BUA.” The manufacturer is just the brand. The grade determines the strength and suitability for your project.

𝑳𝒊𝒌𝒆 , 𝑺𝒉𝒂𝒓𝒆, 𝑪𝒐𝒎𝒎𝒆𝒏𝒕 ,& 𝑭𝒐𝒍𝒍𝒐𝒘 👉 MOSAN for more updates

27/08/2025

The ₦80,000 constant has increased. Check the comment section.

A conservative way to calculate the cost of a building (foundation to roof) in the South East and South South of Nigeria where pad foundation is recommended by the structural engineer.

C = A x no. of floors x 80,000

where C = cost of the building : foundation to roof.

A = Area of the building.

Example, a building (Length = 17m and width 15m) with 3 floors is located at the aforementioned region. Find the cost from foundation to roof.

Solution :

Area : 17 x 15 = 255
no of floors = 3

Now C = 255 x 3 x 80,000 = #61.2m

30/04/2025

Two Conservative Methods of Calculating the Number of Blocks.

First Method : used when the height is known.

Length x height x 10.

Example : calculate the number of blocks for a wall of Length 3.6m and height 3.0m

Solution

3.6 x 3 x 10 x = 108 blocks

Second Method : used when the number of courses (or coaches) is known.

Length x 2 x number of courses.

Example : calculate the number of blocks for a wall : 3.6m with number of coaches 13.

Solution

3.6 x 2 x 13 = 93.6 blocks , say 100 blocks.

19/12/2024

A conservative way to calculate the cost of a building (foundation to roof) in the South East and South South of Nigeria where pad foundation is recommended by the structural engineer.

C = A x no. of floors x 80,000

where C = cost of the building : foundation to roof.

A = Area of the building.

Example, a building (Length = 17m and width 15m) with 3 floors is located at the aforementioned region. Find the cost from foundation to roof.

Solution :

Area : 17 x 15 = 255
no of floors = 3

Now C = 255 x 3 x 80,000 = #61.2m